Display device

ABSTRACT

A display device includes: a display panel including a first substrate, a second substrate, and a light emitting element layer disposed between the first substrate and the second substrate, where the light emitting element outputs light to the second substrate; a first sound generator disposed on a surface of the first substrate, where the first sound generator vibrates the display panel to output a sound; and a first buffer member disposed on the surface of the first substrate, where a height of the first buffer member is less than a height of the first sound generator.

This application claims priority to Korean Patent Application No.10-2019-0011741, filed on Jan. 30, 2019, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND 1. Field

The disclosure relates to a display device.

2. Description of the Related Art

As the information society develops, the demand for display devices fordisplaying images is increasing in various forms. For example, displaydevices are being applied to various electronic devices such assmartphones, digital cameras, notebook computers, navigation devices,and smart televisions. The display devices may be flat panel displaydevices such as liquid crystal display devices, field emission displaydevices, and organic light emitting display devices.

SUMMARY

A display device may include a display panel for displaying an image anda speaker for providing sound. Conventionally, due to space limitationsof the display device, the speaker may be disposed on a lower surface ora side of a display panel, in this case, although it is desirable forsound output from the speaker to be output from the front of the displaydevice, the sound is output from the back of the display device or froma side of the display device. Therefore, sound quality may be reduced.

Embodiments of the disclosure provide a display device with improvedsound quality by outputting a sound from the front of the display deviceby vibrating a display panel using a sound generator.

Embodiments of the disclosure also provide a display device in which adisplay panel is prevented from being damaged when the display panelvibrates.

According to an embodiment of the disclosure, a display device includes:a display panel including a first substrate, a second substrate, and alight emitting element layer disposed between the first substrate andthe second substrate, where the light emitting element layer outputslight to the second substrate; a first sound generator disposed on asurface of the first substrate, where the first sound generator vibratesthe display panel to output a sound; and a first buffer member disposedon the surface of the first substrate, where a height of the firstbuffer member is less than a height of the first sound generator.

In an embodiment, the display device may further include: a lower coverdisposed on the surface of the first substrate; and a circuit boarddisposed on a first surface of the lower cover.

In an embodiment, the first substrate and the first buffer member may bespaced apart from each other with a gap therebetween.

In an embodiment, the height of the first buffer member may be less thana distance between the surface of the first substrate and a secondsurface of the lower cover, which is opposite to the first surface.

In an embodiment, the first buffer member may comprise: a first basefilm; a first buffer layer disposed on a surface of the first base film;an adhesive layer disposed on the first buffer layer; and a firstsacrificial layer disposed between the first buffer layer and theadhesive layer.

In an embodiment, the adhesive layer may be attached to the lower coveror the circuit board.

In an embodiment, the first buffer member may be attached to the secondsurface of the lower cover which faces the surface of the firstsubstrate.

In an embodiment, the gap between the first substrate and the firstbuffer member may be less than a gap between the first substrate and thelower cover.

In an embodiment, the display device may further include a blockingmember disposed between the first substrate and the lower cover.

In an embodiment, the first buffer member may be attached to a surfaceof the circuit board which faces the surface of the first substrate.

In an embodiment, the height of the first buffer member may be less thana distance between the surface of the first substrate and the surface ofthe circuit board.

In an embodiment, the display device may further include a blockingmember disposed between the first substrate and the circuit board.

In an embodiment, a height of the blocking member may be greater thanthe height of the first buffer member.

In an embodiment, the blocking member may include: a second base film; asecond buffer layer disposed on a surface of the second base film; afirst adhesive layer disposed on the second buffer layer; a secondadhesive layer disposed on another surface of the second base film; anda second sacrificial layer disposed between the second buffer layer andthe first adhesive layer.

In an embodiment, the display device may further include a heatdissipation film attached onto the surface of the first substrate, wherethe first adhesive layer may be attached to the heat dissipation film,and the second adhesive layer may be attached to the lower cover or thecircuit board.

In an embodiment, the display device may further include a timingcontrol circuit disposed on the circuit board, where the timing controlcircuit controls driving timing of the display panel.

In an embodiment, the display device may further include a sound drivingcircuit disposed on the circuit board, where the sound driving circuitoutputs a first sound signal to the first sound generator.

In an embodiment, the display device may further include a fixing memberwhich fixes the circuit board to the lower cover, where the fixingmember includes a protrusion which is disposed through the lower coverand the circuit board and protrudes from the second surface of the lowercover, where the protrusion is inserted into the first buffer member.

In an embodiment, the first sound generator may comprise: a bobbindisposed on the surface of the first substrate; a voice coil whichsurrounds the bobbin; a magnet disposed on the bobbin and spaced apartfrom the bobbin; and a lower plate disposed on the magnet and fixed tothe lower cover or the circuit board by a fixing member.

In an embodiment, the display device may further include: a third soundgenerator disposed on the surface of the first substrate; and a soundcircuit board electrically connected to the third sound generator totransmit a sound signal to the third sound generator.

In an embodiment, the third sound generator may include: a firstelectrode which receives a first driving voltage; a second electrodewhich receives a second driving voltage; and a vibration layer disposedbetween the first electrode and the second electrode, where thevibration layer includes a piezoelectric element which contracts orexpands in response to the first driving voltage applied to the firstelectrode and the second driving voltage applied to the secondelectrode.

In an embodiment, the display device may further include: flexible filmsconnected to the first substrate of the display panel; a source circuitboard connected to the flexible films; and a cable which connects thecircuit board and the source circuit board to each other.

In an embodiment, a first hole may be defined through the lower cover,and the cable may be disposed through the first hole .

In an embodiment, the source circuit board may be disposed on thesurface of the first substrate, and the circuit board may be disposed onthe first surface of the lower cover.

In an embodiment, a second hole may be defined through the lower cover,and the sound circuit board may be disposed through the second hole.

In an embodiment, the source circuit board and the circuit board may bedisposed on the first surface of the lower cover.

In an embodiment, the display device may further include a second buffermember which overlaps the third sound generator, where the second buffermember and the third sound generator are spaced apart from each otherwith a gap therebetween.

In an embodiment, the display device may further include a second buffermember disposed on the third sound generator, where the second buffermember and the lower cover are spaced apart from each other with a gaptherebetween.

According to another embodiment of the disclosure a display deviceincludes: a display panel including a first substrate; a lower coverdisposed on a surface of the first substrate; a first sound generatordisposed on the surface of the first substrate, where the first soundgenerator vibrates the display panel to output a sound; and a firstbuffer member disposed on the surface of the first substrate, where aheight of the first buffer member is equal to or less than a distancebetween the first substrate and the lower cover.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other embodiments will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a display device according to anembodiment;

FIG. 2 is an exploded perspective view of the display device accordingto the embodiment;

FIG. 3 is a bottom view of an embodiment of the display device accordingto the embodiment;

FIG. 4 is a bottom view of an embodiment of the display device when alower cover and a control circuit board are omitted from FIG. 3;

FIG. 5 is a side view of an embodiment of the display device of FIG. 2;

FIG. 6 is a bottom view of a heat dissipation film, an adhesive member,a blocking member and first through fourth sound generators of thedisplay device;

FIG. 7 is a cross-sectional view of an embodiment of a display area of adisplay panel;

FIG. 8 is a cross-sectional view of an embodiment of the first soundgenerator and the second sound generator of FIG. 3;

FIG. 9 is a cross-sectional view of an embodiment of a first buffermember illustrated in FIG. 8;

FIGS. 10A and 10B illustrate a vibration of the display panel by thefirst sound generator of FIG. 8;

FIG. 11 is a graph illustrating the vibration displacement with respectto the vibration frequency of the display panel by the first soundgenerator;

FIG. 12 is a cross-sectional view an alternative embodiment of the firstsound generator and the second sound generator of FIG. 3;

FIG. 13 is an enlarged view of area A of FIG. 5;

FIG. 14 is a perspective view of an embodiment of the third soundgenerator of FIG. 4;

FIG. 15 is a cross-sectional view taken along line of FIG. 14;

FIG. 16 illustrates an embodiment of a method of vibrating a vibrationlayer disposed between a first branch electrode and a second branchelectrode of the third sound generator;

FIGS. 17A and 17B are side views illustrating a vibration of the displaypanel by the vibration of the third sound generator illustrated in FIGS.14 and 15;

FIG. 18 is a bottom view of an embodiment of the display deviceaccording to the invention;

FIG. 19 is a bottom view of an alternative embodiment of the displaydevice according to the invention;

FIG. 20 is a bottom view of another alternative embodiment of thedisplay device according to the invention;

FIG. 21 is a bottom view of another alternative embodiment of thedisplay device according to the invention;

FIG. 22 is a bottom view of another alternative embodiment of thedisplay device according to the invention;

FIG. 23 is a bottom view of another alternative embodiment of thedisplay device according to the invention;

FIG. 24 is a side view of the display device of FIG. 23;

FIG. 25 is a cross-sectional view taken along line IV-IV′ of FIG. 23;

FIG. 26 is a bottom view of an alternative embodiment of the displaydevice according to the invention;

FIG. 27 is a bottom view of an embodiment of the display device of FIG.26 when a lower cover and a control circuit board are omitted;

FIG. 28 is a side view of the display device of FIG. 26;

FIG. 29 is a bottom view of another alternative embodiment of thedisplay device according to the invention; and

FIG. 30 is a side view of the display device of FIG. 29.

FIG. 31 is a side view of another alternative of the display device ofFIG. 2; and

FIG. 32 is a side view of another alternative of the display device ofFIG. 2.

DETAILED DESCRIPTION

The invention now will be described more fully hereinafter withreference to the accompanying drawings, in which various embodiments areshown. This invention may, however, be embodied in many different forms,and should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. Like reference numerals refer tolike elements throughout.

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

It will be understood that, although the terms “first,” “second,”“third” etc, may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer orsection” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” “At least one of A and B” means “Aand/or B.” As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. It will befurther understood that the terms “comprises” and/or “comprising,” or“includes” and/or “including” when used in this specification, specifythe presence of stated features, regions, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, regions, integers, steps,operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then heoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system).

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Hereinafter, embodiments of the invention will be described in detailwith reference to the accompanying drawings.

For convenience of description, embodiments where a display device 10 isan organic light emitting display device using organic light emittingelements as light emitting elements, but the disclosure is not limitedthereto. Alternatively, the display device 10 may be an inorganic lightemitting display device using micro-light emitting diodes or inorganicsemiconductors (inorganic light emitting diodes) as light emittingelements.

FIG. 1 is a perspective view of a display device 10 according to anembodiment. FIG. 2 is an exploded perspective view of the display device10 according to an embodiment.

Referring to FIGS. 1 and 2, an embodiment of the display device 10includes a set cover 100, a display panel 110, source driving circuits121, flexible films 122, a heat dissipation film 130, source circuithoards 140, cables 150, a control circuit board 160, a timing controlcircuit 170, and a lower cover 180.

In the specification, the terms “upper”, “top” and “upper surface”indicate a direction in which a second substrate 112 is disposed withrespect to a first substrate 111 of the display panel 110, that is, aZ-axis direction, and the terms “lower,” “bottom” and “lower surface”indicate a direction in which the heat dissipation film 130 is disposedwith respect to the first substrate 111 of the display panel 110, thatis, a direction opposite to the Z-axis direction. In addition, “left,”“right,” “up” and “down” indicate directions when the display panel 110is viewed in a plane. For example, “left” indicates an X-axis direction,“right” indicates a direction opposite to the X-axis direction, “up”indicates a Y-axis direction, and “down” indicates a direction oppositeto the Y-axis direction.

The set cover 100 may surround or cover edges of the display panel 110.The set cover 100 may cover a non-display area excluding a display areaof the display panel 110. In an embodiment, the set cover 100 mayinclude an upper set cover 101 and a lower set cover 102 as illustratedin FIG. 2. The upper set cover 101 may cover edge portions of an uppersurface of the display panel 110, and the lower set cover 102 may coverlower and side surfaces of the display panel 110. The upper set cover101 and the lower set cover 102 may be coupled to each other by a fixingmember such as a screw or an adhesive member such as a double-sided tapeor an adhesive. The upper set cover 101 and the lower set cover 102 mayinclude or be made of a plastic, a metal or a combination thereof.

The display panel 110 may be rectangular in a plan view. In oneembodiment, for example, the display panel 110 may have a rectangularplanar shape having long sides in a first direction (X-axis direction)and short sides in a second direction (Y-axis direction) as illustratedin FIG. 2. Each corner where a long side extending in the firstdirection (X-axis direction) meets a short side extending in the seconddirection (Y-axis direction) may be right-angled or may he rounded witha predetermined curvature. The planar shape of the display panel 110 isnot limited to the rectangular shape, but may also be variously modifiedto have another polygonal shape, a circular shape or an ellipticalshape.

In FIG. 2, the display panel 110 is flat. However, the disclosure is notlimited to this case. The display panel 110 may also be curved or bentwith a predetermined curvature.

The display panel 110 may include the first substrate 111 and the secondsubstrate 112. The first substrate 111 and the second substrate 112 maybe rigid or flexible. The first substrate 111 may include or be made ofa glass or a plastic, and the second substrate 112 may include or bemade of glass, plastic, an encapsulation film, or a barrier film. Theplastic may be polyethersulphone (“PES”), polyacrylate (“PA”),polyarylate (“PAR”), polyetherimide (“PEI”), polyethylene naphthalate(“PEN”), polyethylene terepthalate (“PET”), polyphenylene sulfide(“PPS”), polyallylate, polyimide (“PI”), polycarbonate (“PC”), cellulosetriacetate (“CAT”), cellulose acetate propionate (“CAP”), or acombination thereof. The encapsulation film or the barrier film may be afilm in which a plurality of inorganic layers are stacked one onanother.

In an embodiment, the display panel 110 may include a thin-filmtransistor layer TFTL, a light emitting element layer EML, a filler FL,a light wavelength conversion layer QDL, and a color filter layer CFL asillustrated in FIG. 7. In such an embodiment, the first substrate 111may be a thin-film transistor substrate on which the thin-filmtransistor layer TFTL, the light emitting element layer EML and athin-film encapsulation layer 345 are disposed, the second substrate 112may be a color filter substrate on which the wavelength conversion layerQDL and the color filter layer CFL are disposed, and the filler FL maybe disposed between the thin-film encapsulation layer 345 on the firstsubstrate 111 and the wavelength conversion layer QDL on the secondsubstrate 112. The thin-film transistor layer TFTL, the light emittingelement layer EML, the filler FL, the wavelength conversion layer QDLand the color filter layer CFL of the display panel 110 (collectivelyshown as a layer 113 in FIG. 5) will be described in detail later withreference to FIG. 7.

In such an embodiment, an additional film 114 (shown in FIG. 5) may bedisposed on the second substrate 112. In one embodiment, for example,the additional film 114 may be an antireflective film.

A side of each of the flexible films 122 may be attached onto a surfaceof an element on the first substrate 111 of the display panel 110, andthe other side of each of the flexible films 122 may be attached onto asurface of one of the source circuit boards 140. In an embodiment, sincethe first substrate 111 is larger in size than the second substrate 112,a side of an element on the first substrate 111 may be exposed withoutbeing covered by the second substrate 112. The flexible films 122 may beattached to the exposed side of an element on the first substrate 111which is not covered by the second substrate 112. Each of the flexiblefilms 122 may be attached onto the surface of the first substrate 111and the surface of one of the source circuit boards 140 by using ananisotropic conductive film.

Each of the flexible films 122 may be a tape carrier package or a chipon film. Each of the flexible films 122 is bendable. Therefore, theflexible films 122 may be bent toward a lower surface of the firstsubstrate 111 as illustrated in FIGS. 4 and 6. In such an embodiment,the source circuit boards 140, the cables 150. and the control circuitboard 160 may be disposed on the lower surface of the first substrate111.

In an embodiment shown in FIG. 2, eight flexible films 122 are on thefirst substrate 111 of the display panel 110, but the number of theflexible films 122 is not limited thereto.

The source driving circuits 121 may be disposed or mounted on surfacesof the flexible films 122, respectively. The source driving circuits 121may be defined by or formed as integrated circuits. The source drivingcircuits 121 convert digital video data into analog data voltages basedon a source control signal of the timing control circuit 170 and supplythe analog data voltages to data lines of the display panel 110 throughthe flexible films 122.

Each of the source circuit boards 140 may be connected to the controlcircuit board 160 via the cables 150. In such an embodiment, each of thesource circuit boards 140 may include first connectors 151 a forconnection to the cables 150. The source circuit boards 140 may beflexible printed circuit boards or printed circuit boards. The cables150 may be flexible cables.

The control circuit board 160 may be connected to the source circuitboards 140 via the cables 150. In an embodiment, the source circuitboards 140 may include first connectors 151 for connection to the cables150, and the control circuit board 160 may include second connectors 152for connection to the cables 150. The control circuit board 160 may be aflexible printed circuit board or a printed circuit board.

In an embodiment of FIG. 2 four cables 150 connect the source circuitboards 140 and the control circuit board 160, but the number of thecables 150 is not limited thereto. In FIG. 2, two source circuit boards140 are illustrated, but the number of the source circuit boards 140 isnot limited thereto.

The timing control circuit 170 may be disposed or mounted on a firstsurface of the control circuit board 160. The timing control circuit 170may be defined by or formed as an integrated circuit. The tinningcontrol circuit 170 may receive digital video data and timing signalsfrom a system on chip of a system circuit board and generate a sourcecontrol signal for controlling the timings of the source drivingcircuits 121 based on the timing signals.

The system on chip may be disposed or mounted on the system circuitboard connected to the control circuit board 160 via another flexiblecable and may be defined by or formed as an integrated circuit. Thesystem on chip may be a processor of a smart television, a centralprocessing unit (“CPU”) or graphics card of a computer or notebook, oran application processor of a smartphone or tablet personal computer(“PC”). The system circuit board may be a flexible printed circuit boardor a printed circuit board.

A power supply circuit (not shown) may be additionally attached onto thefirst surface of the control circuit board 160. The power supply circuitmay generate voltages used for driving the display panel 110 from mainpower received from the system circuit board and supply the generatedvoltages to the display panel 110. In one embodiment, for example, thepower supply circuit may generate a high-potential voltage, alow-potential voltage and an initialization voltage for driving organiclight emitting elements and supply the generated voltages to the displaypanel 110. In such an embodiment, the power supply circuit may generatedriving voltages for driving the source driving circuits 121, the timingcontrol circuit 170, etc. and supply the generated voltages. The powersupply circuit may be defined by or formed as an integrated circuit.Alternatively, the power supply circuit may be disposed on a powercircuit board formed separately from the control circuit board 160. Thepower circuit board may be a flexible printed circuit board or a printedcircuit board.

In an embodiment, the heat dissipation film 130 may be disposed on asurface of the first substrate 111 which does not face the secondsubstrate 112, that is, on the lower surface of the first substrate 111.In such an embodiment, first through fourth sound generators 210 through240 may be disposed on a surface of the heat dissipation film 130 whichdoes not face the first substrate 111, that is, on a lower surface ofthe heat dissipation film 130. The heat dissipation film 130 dissipatesheat generated by the first through fourth sound generators 210 through240. In such an embodiment, the heat dissipation film 130 may include alayer including a material having high thermal conductivity, such asgraphite, silver (Ag), copper (Cu) or aluminum (Al).

In an embodiment, the heat dissipation film 130 may include a pluralityof graphite layers or a plurality of metal layers formed in the firstdirection (X-axis direction) and the second direction (Y-direction), notin a third direction (Z-direction). In such an embodiment, since theheat generated by the first through fourth sound generators 210 through240 is allowed to be diffused in the first direction (X-axis direction)and the second direction (Y-axis direction), the heat may be releasedmore effectively. Herein, the first direction (X-axis direction) may bea width direction (or a horizontal direction) of the display panel 110,the second direction (Y-axis direction) may be a length direction (or avertical direction) of the display panel 110, and the third direction(Z-axis direction) may be a thickness direction of the display panel110. Therefore, the heat dissipation film 130 may minimize the effect ofthe heat generated by the first through fourth sound generators 210through 240 on the display panel 110.

In an embodiment, as shown in FIG. 5, a thickness D1 of the heatdissipation film 130 may be greater than a thickness D2 of the firstsubstrate 111 and a thickness D3 of the second substrate 112 toeffectively prevent the heat generated by the first through fourth soundgenerators 210 through 240 from affecting the display panel 110.

The size of the heat dissipation film 130 ay be smaller than that of thefirst substrate 111. Therefore, an edge of the surface of the firstsubstrate 111 may be exposed without being covered by the heatdissipation film 130.

In an alternative embodiment, the heat dissipation film 130 may beomitted, and in such an embodiment, elements disposed on the surface ofthe heat dissipation film 130 can be understood as being disposed on thesurface of the first substrate 111.

The first through fourth sound generators 210 through 240 may bevibration devices capable of vibrating the display panel 110 in thethird direction (Z-axis direction). In such an embodiment, the displaypanel 110 may serve as a diaphragm for outputting sound.

In an embodiment, each of the first sound generator 210 and the secondsound generator 220 may be an exciter that vibrates the display panel110 by generating a magnetic force using a voice coil as illustrated inFIGS. 8, 10A and 10B. In such an embodiment, each of the third soundgenerator 230 and the fourth sound generator 240 may be a piezoelectricelement that vibrates the display panel 110 by contracting or expandingin response to an applied voltage as illustrated in FIGS. 12, 13, 14,15A and 15B.

In an embodiment, the first sound generator 210 and the second soundgenerator 220 may serve as mid- and low-sound generators that outputsound in mid and low bands, and the third sound generator 230 and thefourth sound generator 240 may serve as high-sound generators thatoutput sound in a high band higher than that of the sound output by thefirst sound generator 210 and the second sound generator 220. In such anembodiment, the display device 10 may provide right stereo sound usingthe first sound generator 210 and the third sound generator 230 andprovide left stereo sound using the second sound generator 220 and thefourth sound generator 240. Therefore, the display device 10 may provide2.0 channel stereo sound.

Alternatively, the third sound generator 230 and the fourth soundgenerator 240 may be omitted, and the first sound generator 210 and thesecond sound generator 220 may respectively serve or function as mid-and high-sound generators that output sound in mid and high bands. Insuch an embodiment, the display device 10 may provide right stereo soundusing the first sound generator 210 and provide left stereo sound usingthe second sound generator 220. Therefore, the display device 10 mayprovide 2.0 channel stereo sound.

Alternatively, the second sound generator 220 may be omitted, the firstsound generator 210 may serve as a low-sound generator that outputssound in a low band, and the third sound generator 230 and the fourthsound generator 240 may serve as high-sound generators that output soundin a high band higher than that of the sound output by the first soundgenerator 210. In such an embodiment, the display device 10 may providelow-pitched sound using the first sound generator 210, provide rightstereo sound using the third sound generator 230 and provide left stereosound using the fourth sound generator 240. Therefore, the displaydevice 10 may provide 2.1 channel stereo sound.

Alternatively, the second sound generator 220, the third sound generator230 and the fourth sound generator 240 may be omitted, and the firstsound generator 210 may serve as a mid- and high-sound generator thatoutputs sound in mid and high bands. In such an embodiment, the displaydevice 10 may provide mid- and high-pitched sound using the first soundgenerator 210. Therefore, the display device 10 may provide monauralsound.

In an embodiment, the display device 10 includes four sound generators210 through 240 as shown in FIG. 2, but the number of the soundgenerators 210 through 240 is not limited thereto. The first soundgenerator 210 and the second sound generator 220 will be described indetail later with reference to FIGS. 8, 10A and 10B. The third soundgenerator 230 and the fourth sound generator 240 will be described indetail later with reference to FIGS. 12, 13, 14, 15A and 15B.

The lower cover 180 may be disposed on the surface of the heatdissipation film 130. The lower cover 180 may be attached to the edgesof the surface of the first substrate 111 of the display panel 110 witha first adhesive member 115. The first adhesive member 115 may be adouble-sided tape including a buffer layer such as foam. The lower cover180 may be metal or tempered glass.

In an embodiment, as described above, the display device 10 outputssound using the display panel 110 as a diaphragm through the firstthrough fourth sound generators 210 through 240. In such an embodiment,since sound ay be output from the front of the display device 10, soundquality may be improved. In such an embodiment, the first through fourthsound generators 210 through 240 allow a speaker typically provided on alower surface or a side of a conventional display panel to be omitted.

In an embodiment, the display device 10 may be a medium- and large-sizeddisplay device including a plurality of source driving circuits 121 inFIGS. 1 and 2, but the disclosure is not limited thereto. Alternatively,the display device may also be a small-sized display device including asingle source driving circuit 121. In such an embodiment, the flexiblefilms 122, the source circuit boards 140, and the cables 150 may beomitted. In such an embodiment, the source driving circuits 121 and thetiming control circuit 170 may be integrated into a single integratedcircuit and then attached onto a single flexible circuit board ordisposed on the first substrate 111 of the display panel 110. Herein,the medium- and large-sized display device include monitors andtelevisions, for example, and the small-sized display device includesmartphones and tablet PCs, for example.

FIG. 3 is a bottom view of an embodiment of the display device 10 ofFIG. 2. FIG. 4 is a bottom view of an embodiment of the display device10 when the lower cover 180 and the control circuit board 160 areomitted from FIG. 3. FIG. 5 is a side view of an embodiment of thedisplay device 10 of FIG. 2.

Referring to FIGS. 3 through 5, in an embodiment of the display device10, the flexible films 122 may be bent toward the lower surface of theheat dissipation film 130. Therefore, the source circuit boards 140 maybe disposed on the surface of the heat dissipation film 130.

In such an embodiment, where the source circuit boards 140 are disposedon the surface of the heat dissipation film 130, the control circuitboard 160 is disposed on a first surface of the lower cover 180. In suchan embodiment, the source circuit boards 140 are disposed between thesurface of the heat dissipation film 130 and a second surface of thelower cover 180. Therefore, the cables 150 connected to the firstconnectors 151 a of the source circuit boards 140 may be connected tothe second connectors 152 of the control circuit board 160 through firstcable holes CH1 defined through the lower cover 180.

The third sound generator 230 and the fourth sound generator 240 may beattached onto the surface of the heat dissipation film 130 with anadhesive member such as a double-sided adhesive. The third soundgenerator 230 may be connected to a second connector 151 b of a sourcecircuit board 140 by a first sound circuit board 250, and the fourthsound generator 240 may be connected to a second connector 151 b of asource circuit board 140 by a second sound circuit board 260. A firstpad and a second pad, which are connected to a first electrode and asecond electrode disposed on a surface of the third sound generator 230,may be disposed on a side of the first sound circuit board 250. A firstpad and a second pad, which are connected to a first electrode and asecond electrode disposed on a surface of the fourth sound generator240, may be disposed on a side of the second sound circuit board 260.Connection portions for connection to the second connectors 151 b of thesource circuit boards 140 may be disposed on the other side of the firstsound circuit board 250 and the other side of the second sound circuitboard 260. That is, the third sound generator 230 may be electricallyconnected to the source circuit board 140 by the first sound circuitboard 250, and the fourth sound generator 240 may be electricallyconnected to the source circuit board 140 by the second sound circuitboard 260. The first sound circuit board 250 and the second soundcircuit board 260 may be flexible printed circuit boards or flexiblecables.

A sound driving circuit 171, the first sound generator 210, and thesecond sound generator 220 as well as the timing control circuit 170 maybe disposed on the control circuit board 160.

The sound driving circuit 171 may receive a sound control signal, whichis a digital signal, from the system circuit board. The sound drivingcircuit 171 may be defined by or formed as an integrated circuit and maybe disposed on the control circuit board 160 or the system circuitboard. The sound driving circuit 171 may include a digital signalprocessor (“DSP”) for processing a sound control signal which is adigital signal, a digital-to-analog converter (“DAC”) for converting thedigital signal processed by the DSP into driving voltages which areanalog signals, and an amplifier (“AMP”) for amplifying the analogdriving voltages output from the DAC and outputting the amplified analogdriving voltages. The analog driving voltages may include a positivedriving voltage and a negative driving voltage.

In an embodiment, the sound driving circuit 171 may generate a firstsound signal including a first driving voltage (hereinafter, (1A)^(th)driving voltage) and a second first driving voltage (hereinafter,(1B)^(th) driving voltage) for driving the first sound generator 210,and a second sound signal including a first second driving voltage(hereinafter, (2A)^(th) driving voltage) and a second second drivingvoltage (hereinafter (2B)^(th) driving voltage) for driving the secondsound generator 220 in response to a sound control signal. In such anembodiment, the sound driving circuit 171 may generate a third soundsignal including a first third driving voltage (hereinafter (3A)^(th)driving voltage) and a second third driving voltage (hereinafter,(3B)^(th) driving voltage) for driving the third sound generator 230,and a fourth sound signal including a first fourth driving voltage(hereinafter, (4A)^(th) driving voltage) and a second fourth drivingvoltage (hereinafter, (4B)^(th) driving voltage) for driving the fourthsound generator 240 in response to the sound control signal.

The first sound generator 210 may receive the first sound signalincluding the (1A)^(th) driving voltage and the (1B)^(th) drivingvoltage from the sound driving circuit 171. The first sound generator210 may output sound by vibrating the display panel 110 based on the(1A)^(th) driving voltage and the (1B)^(th) driving voltage.

The second sound generator 220 may receive the second sound signalincluding the (2A)^(th) driving voltage and the (2B)^(th) drivingvoltage from the sound driving circuit 171. The second sound generator220 may output sound by vibrating the display panel 110 based on the(2A)^(th) driving voltage and the (2B)^(th) driving voltage.

In an embodiment, where the sound driving circuit 171, the first soundgenerator 210 and the second sound generator 220 are disposed on thecontrol circuit board 160 as illustrated in FIG. 3, the sound drivingcircuit 171 and the first sound generator 210 may be electricallyconnected to each other by metal lines of the control circuit board 160.In such an embodiment, the sound driving circuit 171 and the secondsound generator 220 may be electrically connected to each other by metallines of the control circuit board 160.

The third sound generator 230 may receive the third sound signalincluding the (3A)^(th) driving voltage and the (3B)^(th) drivingvoltage from the sound driving circuit 171. The third sound generator230 may output sound by vibrating the display panel 110 based on the(3A)^(th) driving voltage and the (3B)^(th) driving voltage.

The fourth sound generator 240 may receive the fourth sound signalincluding the (4A)^(th) driving voltage and the (4B)^(th) drivingvoltage from the sound driving circuit 171. The fourth sound generator240 may output sound by vibrating the display panel 110 based on the(4A)^(th) driving voltage and the (4B)^(th) driving voltage.

In embodiments of the invention, the number of sound generatorsimplemented as exciters and the number of sound generators implementedas piezoelectric elements are not limited to those illustrated in FIGS.3 through 5.

In an embodiment, the sound driving circuit 171 may be disposed on thecontrol circuit board 160 as illustrated in FIG. 3, and the third soundgenerator 230 and the fourth sound generator 240 may be disposed on thesurface of the heat dissipation film 130. In such an embodiment, thethird sound signal of the sound driving circuit 171 may be transmittedto the third sound generator 230 via a cable 150, the source circuitboard 140, and the first sound circuit board 250. In an embodiment, thefourth sound signal of the sound driving circuit 171 may be transmittedto the fourth sound generator 240 via a cable 150, the source circuitboard 140, and the second sound circuit board 260.

A first buffer member 190 effectively prevents the display panel 110from colliding with the lower cover 180 and being damaged due to largevibration displacement of the display panel 110 when the display panel110 is vibrated by the first sound generator 210 and by the second soundgenerator 220. In such an embodiment, the first buffer member 190 maysurround each of the first sound generator 210 and the second soundgenerator 220. In one embodiment, for example, as illustrated in FIG. 3,the first buffer member 190 may surround each of the first soundgenerator 210 and the second sound generator 220 in a circular shapewhen seen in a plan view. In such an embodiment, a distance between thefirst buffer member 190 and the first sound generator 210 and betweenthe first buffer member 190 and the second sound generator 220 may besubstantially constant.

In an embodiment, the first buffer member 190 may be attached to asecond surface of the control circuit board 160 or the second surface ofthe lower cover 180 as illustrated in FIG. 5. Alternatively, the firstbuffer member 190 may be attached onto the surface of the heatdissipation film 130 as illustrated in FIG. 31. In such an embodiment,the height of the first buffer member 190 is less than the distancebetween the surface of the heat dissipation film 130 and the secondsurface of the control circuit board 160. In such an embodiment, thefirst buffer member 190 and the heat dissipation film 130 is spacedapart from each other with a gap therebetween. In an embodiment, theheight of the first buffer member 190 may be less than a height H1 ofthe first sound generator 210 and a height of the second sound generator220. The height H1 of the first sound generator 210 may be a distancefrom a bobbin 212 of the first sound generator 210 to a lower platethereof as illustrated in FIG. 5.

Alternatively, the first buffer member 190 may be attached to thesurface of the heat dissipation film 130 and the second surface of thecontrol circuit board 160 or the second surface of the lower cover 180as illustrated in FIG. 32. In such an embodiment, the height of thefirst buffer member 190 may be substantially equal to the distancebetween the surface of the heat dissipation film 130 and the secondsurface of the control circuit board 160.

A second buffer member 190 c effectively prevents the display panel 110from colliding with the lower cover 180 and being damaged due tosubstantial vibration displacement of the display panel 110 when thedisplay panel 110 is vibrated by the third sound generator 230 and thefourth sound generator 240. In such an embodiment, the second buffermember 190 c may overlap the third sound generator 230 and the fourthsound generator 240. in one embodiment, for example, the second buffermember 190 c may be attached to the second surface of the lower cover180 or the second surface of the control circuit board 160 asillustrated in FIG. 5. Alternatively, the second buffer member 190 c maybe disposed on the surface of the third sound generator 230 and thesurface of the fourth sound generator 240.

In an embodiment, the height of the second buffer member 190 c may beless than that of the first buffer member 190. In such an embodiment,the height of the second buffer member 190 c is less than the distancebetween the first surface of the heat dissipation film 130 and thesecond surface of the control circuit board 160 or the second surface ofthe lower cover 180. Therefore, in an embodiment where the second buffermember 190 c is attached to the second surface of the lower cover 180 orthe second surface of the control circuit board 160 as illustrated inFIG. 5, a gap may exist between the second buffer member 190 c and thethird sound generator 230 and between the second buffer member 190 c andthe fourth sound generator 240. Alternatively, in an embodiment wherethe second buffer member 190 c is disposed on the surface of the thirdsound generator 230 and the surface of the fourth sound generator 240,there may a gap between the second buffer member 190 c and the controlcircuit board 160 or the lower cover 180.

According to an embodiment, as shown in FIGS. 3 through 5, the thirdsound generator 230 and the source circuit board 140 are connected bythe first sound circuit board 250, and the fourth sound generator 240and the source circuit board 140 are connected by the second soundcircuit board 260. Therefore, in an embodiment where the third soundgenerator 230 and the fourth sound generator 240 are disposed on thesurface of the heat dissipation film 130 while the control circuit board160 is disposed on the first surface of the lower cover 180, the controlcircuit board 160 and the third sound generator 230 may be easily oreffectively electrically connected to each other, and the controlcircuit board 160 and the fourth sound generator 240 may be easily oreffectively electrically connected to each other.

FIG. 6 is a bottom view of the heat dissipation film 130, the adhesivemember 115, a blocking member 200 and the first through fourth soundgenerators 210 through 240 of the display device. In FIG. 6, only thefirst substrate 111, the first adhesive member 115, the heat dissipationfilm 130, the blocking member 200 and the first through fourth soundgenerators 210 through 240 of the display panel 110 are illustrated forease of description. That is, the source driving circuits 121, theflexible films 122, the source circuit boards 140, the cables 150, thecontrol circuit board 160, the timing control circuit 170 and the lowercover 180 are omitted from FIG. 6.

Referring to FIG. 6, as described above, the size of the heatdissipation film 130 may be smaller than that of the first substrate111. Therefore, four edges of the surface of the first substrate 111 maybe exposed without being covered by the heat dissipation film 130.

The first adhesive member 115 may be disposed on the exposed four edgesof the surface of the first substrate 111 which are not covered by theheat dissipation film 130. The first adhesive member 115 may attach thesurface of the first substrate 111 to the second surface of the lowercover 180 as illustrated in FIG. 5. The first adhesive member 115 may bea double-sided tape including a buffer layer such as a foam.

The blocking member 200 may block the propagation of vibrations of thedisplay panel 110 generated by each of the first through fourth soundgenerators 210 through 240 or block the transmission of sound generatedby the vibration of the display panel 110. In an embodiment, theblocking member 200 may be attached to the surface of the heatdissipation film 130 and the second surface of the lower cover 180 toblock the propagation of vibrations of the display panel 110 or thetransmission of sound.

The blocking member 200 may be disposed on four edge portions of theheat dissipation film 130. The blocking member 200 may attach thesurface of the heat dissipation film 130 to the second surface of thelower cover 180. The height of the blocking member 200 is greater thanthe height of the first buffer member 190 and the height of the secondbuffer member 190 c.

The surface of the heat dissipation film 130 may be divided into firstthrough sixth areas A1 through A6 by the blocking member 200 asillustrated in FIG. 6.

The first area A1 is an area where the first sound generator 210 isdisposed and may be defined by the blocking member 200 disposed tosurround the first sound generator 210. The second area A2 is an areawhere the second sound generator 220 is disposed and may be defined bythe blocking member 200 disposed to surround the second sound generator220. The size of the first area A1 and the size of the second area A2may be substantially the same as each other.

The third area A3 is an area where the third sound generator 230 isdisposed and may be defined by the blocking member 200 disposed tosurround the third sound generator 230. The fourth area A4 is an areawhere the fourth sound generator 240 is disposed and may be defined bythe blocking member 200 disposed to surround the four sound generator240. In an embodiment, as shown in FIG. 6, the size of the third area A3and the size of the fourth area A4 may be smaller than the size of thefirst area A1 and the size of the second are A2, respectively.

The fifth area A5 is an area where the source circuit boards 140 aredisposed and may be defined by the blocking member 200 disposed tosurround the source circuit boards 140. The fifth area A5 mayeffectively prevent or substantially reduce the effect of the firstthrough fourth sound generators 210 through 240 of the first throughfourth areas A1 through A4 on the source circuit boards 140, the sourcedriving circuits 121 and the flexible films 122.

The sixth area A6 is an area between the first area A1 and the secondarea A2. No sound generator may be disposed in the sixth area A6. Thesixth area A6 may increase the distance between the first area A1 andthe second area A2. Therefore, in such an embodiment, the effect ofvibrations of the display panel 110 generated by the first soundgenerator 210 of the first area A1 on vibrations of the display panel110 generated by the second sound generator 220 of the second area A2 orthe effect of vibrations of the display panel 110 generated by thesecond sound generator 220 of the second area A2 on vibrations of thedisplay panel 110 generated by the first sound generator 210 of thefirst area Al may be effectively prevented or substantially reduced.

Alternatively, the sixth area A6 may be omitted, and the first area A1and the second area A2 may be disposed adjacent to each other.

According to an embodiment, as shown in FIG. 6, each of the firstthrough fourth sound generators 210 through 240 is surrounded by theblocking member 200. Therefore, the effect of vibrations of the displaypanel 110 generated by each of the first through fourth sound generators210 through 240 on vibrations of the display panel 110 generated by anadjacent sound generator may be effectively prevented or substantiallyreduced. FIG. 7 is a cross-sectional view of an embodiment of thedisplay area of the display panel 110.

Referring to FIG. 7, an embodiment of the display panel 110 may includethe first substrate 111, the second substrate 112, the thin-filmtransistor layer TFTL, the light emitting element layer EML, the fillerFL, the wavelength conversion layer QDL, and the color filter layer CFL.

A buffer layer 302 may be disposed on a surface of the first substrate111 which faces the second substrate 112. The buffer layer 302 may bedisposed on the first substrate 111 to protect thin-film transistors 335and light emitting elements from moisture that may be introduced throughthe first substrate 111 which may be vulnerable to moisture penetration.The buffer layer 302 may include or be composed of a plurality ofinorganic layers stacked alternately. In one embodiment, for example,the buffer layer 302 may be a multilayer in which one or more inorganiclayers including at least one selected from a silicon oxide (SiOx)layer, a silicon nitride (SiNx) layer and SiON are alternately stacked.Alternatively, the buffer layer 302 may be omitted.

The thin-film transistor layer TFTL is disposed on the buffer layer 302.The thin-film transistor layer TFTL includes the thin-film transistors335, a gate insulating layer 336, an interlayer insulating film 337, aprotective layer 338, and a planarization layer 339.

The thin-film transistors 335 are disposed on the buffer layer 302. Eachof the thin-film transistors 335 includes an active layer 331, a gateelectrode 332, a source electrode 333, and a drain electrode 334. In anembodiment, as shown in FIG. 7, each of the thin-film transistors 335 isa top-gate type in which the gate electrode 332 is located above theactive layer 331, but the disclosure is not limited thereto.Alternatively, each of the thin-film transistors 335 may also be abottom-gate type in which the gate electrode 332 is located under theactive layer 331 or a double-gate type in which the gate electrode 332is located both above and under the active layer 331.

The active layers 331 are disposed on the buffer layer 302. The activelayers 331 may include or be made of a silicon-based semiconductormaterial or an oxide-based semiconductor material. A light shieldinglayer may be disposed between the buffer layer 302 and the active layers331 to block external light from entering the active layers 331.

The gate insulating layer 336 may be disposed on the active layers 331.The gate insulating layer 336 may be an inorganic layer, for example, aSiOx layer, a SiNx layer, or a multilayer including or composed of theselayers.

The gate electrodes 332 and gate lines may be disposed on the gateinsulating layer 336. Each of the gate electrodes 332 and the gate linesmay be a single layer or a multilayer including or made of any one ormore of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au),titanium (Ti), nickel (Ni), neodymium (Ne), copper (Cu), and an alloythereof.

The interlayer insulating film 337 may be disposed on the gateelectrodes 332 and the gate lines, The interlayer insulating film 337may be an inorganic layer, for example, a SiOx layer, a SiNx layer, or amultilayer including or composed of these layers.

The source electrodes 333, the drain electrodes 334, and data lines mayhe disposed on the interlayer insulating film 337. Each of the sourceelectrodes 333 and the drain electrodes 334 may be connected to anactive layer 331 through a contact hole defined through the gateinsulating layer 336 and the interlayer insulating film 337. Each of thesource electrodes 333, the drain electrodes 334 and the data lines maybe a single layer or a multilayer including or made of any one or moreof molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium(Ti), nickel (Ni), neodymium (Ne), copper (Cu), and an alloy thereof

The protective layer 338 for insulating the thin-film transistors 335may be disposed on the source electrodes 333, the drain electrodes 334,and the data lines. The protective layer 338 may be an inorganic layer,for example, a SiOx layer, a SiNx layer, or a multilayer including orcomposed of these layers.

The planarization layer 339 may be disposed on the protective layer 338to planarize steps due to the thin-film transistors 335. Theplanarization layer 339 may include or be made of an organic layer suchas acryl resin, epoxy resin, phenolic resin, polyamide resin, orpolyimide resin.

The light emitting element layer EML is disposed on the thin-filmtransistor layer TFTL. The light emitting element layer EML includeslight emitting elements and a pixel defining layer 344.

The light emitting elements and the pixel defining layer 344 aredisposed on the planarization layer 339. The light emitting elements maybe organic light emitting elements. In such an embodiment, each of thelight emitting elements may include an anode 341, a light emitting layer342, and a cathode 343.

The anodes 341 may be disposed on the planarization layer 339. Theanodes 341 may be connected to the drain electrodes 334 of the thin-filmtransistors 335 through contact holes defined through the protectivelayer 338 and the planarization layer 339.

The pixel defining layer 344 may be disposed on the planarization layer339 and may cover edges of the anodes 341 to define pixels. In anembodiment, the pixel defining layer 344 defines subpixels PX1 throughPX3. Each of the subpixels PX1 through PX3 is an area in which the anode341, the light emitting layer 342 and the cathode 343 are sequentiallystacked so that holes from the anode 341 and electrons from the cathode343 combine together in the light emitting layer 342 to emit light.

The light emitting layer 342 is disposed on the anodes 341 and the pixeldefining layer 344. The light emitting layer 342 may be an organic lightemitting layer. The light emitting layer 342 may emit light having ashort wavelength, such as a blue light or an ultraviolet light. The bluelight may have a peak wavelength range of about 450 nanometers (nm) toabout 490 nm, and the ultraviolet light may have a peak wavelength rangeof less than about 450 nm. In such an embodiment, the light emittinglayer 342 may be a common layer commonly disposed to cover all of thesubpixels PX1 through PX3. In such an embodiment, the display panel 110may include the wavelength conversion layer QDL for convertingshort-wavelength light such as a blue light or an ultraviolet lightemitted from the light emitting layer 342 into a red light, a greenlight and a blue light and the color filter layer CFL which transmitseach of the red light, the green light and the blue light.

The light emitting layer 342 may include a hole transporting layer, alight emitting layer, and an electron transporting layer. In addition,the light emitting layer 342 have a tandem structure of two or morestacks, where a charge generating layer may be formed between thestacks.

The cathode 343 is disposed on the light emitting layer 342, The cathode343 may be disposed to cover the light emitting layer 342. The cathode343 may be a common layer commonly disposed to cover all pixels.

The light emitting element layer EML may be a top emission type whichemits light toward the second substrate 112, that is, in an upwarddirection. In such an embodiment, the anodes 341 may include or be madeof a metal material having high reflectivity, such as a stackedstructure (Ti/Al/Ti) of Al and Ti, a stacked structure (ITO/Al/ITO) ofAl and indium tin oxide (“ITO”), an APC alloy, or a stacked structure(ITO/APC/ITO) of an APC alloy and ITO. Here, the APC alloy is an alloyof Ag, palladium (Pd), and Cu. In an embodiment, the cathode 343 mayinclude or be made of a transparent conductive material (“TCO”) capableof transmitting light, such as ITO or indium zinc oxide (“IZO”), or asemi-transmissive conductive material such as magnesium (Mg), Ag or analloy of Mg and Ag. In an embodiment, where the cathode 343 includes oris made of a semi-transmissive conductive material, the light outputefficiency may be increased by a microcavity-effect.

A thin-film encapsulation layer 345 is disposed on the light emittingelement layer EML. The thin-film encapsulation layer 345 may preventoxygen or moisture from permeating the light emitting layer 342 and thecathode 343. In such an embodiment, the thin-film encapsulation layer345 may include at least one inorganic layer. The inorganic layer mayinclude or be made of silicon nitride, aluminum nitride, zirconiumnitride, titanium nitride, hafnium nitride, tantalum nitride, siliconoxide, aluminum oxide, or titanium oxide. In an embodiment, thethin-film encapsulation layer 345 may further include at least oneorganic layer. The organic layer may have a sufficient thickness toprevent particles from penetrating the thin-film encapsulation layer 345and entering the light emitting layer 342 and the cathode 343 Theorganic layer may include at least one of epoxy, acrylate, and urethaneacrylate.

The color filter layer CFL is disposed on a surface of the secondsubstrate 112 which faces the first substrate 111. The color filterlayer CFL may include a black matrix 360 and color filters 370.

The black matrix 360 may be disposed on the surface of the secondsubstrate 112. The black matrix 360 may not overlap the subpixels PX1through PX3 and may overlap the pixel defining layer 344. The blackmatrix 360 may include black dye capable of blocking light or an opaquemetal material.

The color filters 370 may be disposed to overlap the subpixels PX1through PX3. A first color filter 371 may overlap a first subpixel PX1,a second color filter 372 may overlap a second subpixel PX2, and a thirdcolor filter 373 may overlap a third subpixel PX3. In such anembodiment, the first color filter 371 may be a first color lighttransmitting filter that transmits light of a first color, the secondcolor filter 372 may be a second color light transmitting filter thattransmits light of a second color, and the third color filter 373 may bea third color light transmitting filter that transmits light of a thirdcolor. In one embodiment, for example, the first color may be a redcolor, the second color may be a green color, and the third color may bea blue color. In such an embodiment, the peak wavelength range of thered light transmitted through the first color filter 371 may be about620 nm to about 750 nm, the peak wavelength range of the green lighttransmitted through the second color filter 372 may be about 500 nm toabout 570 nm, and the peak wavelength range of the blue lighttransmitted through the third color filter 373 may be about 450 nm toabout 490 nm.

In an embodiment, edges of two adjacent color filters may overlap theblack matrix 360. Therefore, the black matrix 360 may effectivelyprevent color mixing that occurs when light emitted from the lightemitting layer 342 of a subpixel travels to a color filter of anadjacent subpixel.

An overcoat layer may be disposed on the color filters 370 to planarizea step due to the black matrix 360. Alternatively, the overcoat layermay be omitted.

The wavelength conversion layer QDL is disposed on the color filterlayer CFL. The wavelength conversion layer QDL may include a firstcapping layer 351, a first wavelength conversion layer 352, a secondwavelength conversion layer 353, a third wavelength conversion layer354, a second capping layer 355, an interlayer organic film 356, and athird capping layer 357.

The first capping layer 351 may be disposed on the color filter layerCFL. The first capping layer 351 may effectively prevent moisture oroxygen from permeating into the first wavelength conversion layer 352,the second wavelength conversion layer 353 and the third wavelengthconversion layer 354 from the outside through the color filter layerCFL. The first capping layer 351 may include or be made of an inorganiclayer such as silicon nitride, aluminum nitride, zirconium nitride,titanium nitride, hafnium nitride, tantalum nitride, silicon oxide,aluminum oxide, or titanium oxide.

The first wavelength conversion layer 352 the second wavelengthconversion layer 353 and the third wavelength conversion layer 354 maybe disposed on the first capping layer 351.

The first wavelength conversion layer 352 may overlap the first subpixelPX1. The first wavelength conversion layer 352 may convertshort-wavelength light such as a blue light or an ultraviolet lightemitted from the light emitting layer 342 of the first subpixel PX intolight of the first color. In such an embodiment, the first wavelengthconversion layer 352 may include a first base resin, a first wavelengthshifter, and a first scatterer.

The first base resin may be a material having high light transmittanceand high dispersion characteristics for the first wavelength shifter andthe first scatterer. In one embodiment, for example, the first baseresin may include an organic material such as epoxy resin, acrylicresin, cardo resin, or imide resin.

The first wavelength shifter may convert or shift the wavelength rangeof incident light. The first wavelength shifter may be quantum dots, aquantum rod, or a phosphor. In one embodiment, for example, the firstwavelength shifter is quantum dots, which may be a semiconductornanocrystalline material and have a specific band gap according to thecomposition and size thereof. Thus, the first wavelength shifter mayabsorb incident light and then emit light having a unique wavelength. Insuch an embodiment, the first wavelength shifter may have a core-shellstructure including a core containing a nanocrystal and a shellsurrounding the core. In such an embodiment, the nanocrystal that formsthe core may include a group IV nanocrystal, a group II-VI compoundnanocrystal, group III-V compound nanocrystal, a group IV-VInanocrystal, and combinations of the same. The shell may serve as aprotective layer for maintaining semiconductor characteristics bypreventing chemical denaturation of the core and/or as a charging layerfor giving electrophoretic characteristics to the quantum dot. In suchan embodiment, the shell may be a single layer or a multilayer. Theshell may be, for example, a metal or non-metal oxide, a semiconductorcompound, or a combination thereof.

The first scatterer play have a refractive index different from that ofthe first base resin and form an optical interface with the first baseresin. In one embodiment, for example, the first scatterer may be lightscattering particles. In one embodiment, for example, the firstscatterer may be metal oxide particles including titanium oxide (TiO₂),silicon oxide (SiO₂), zirconium oxide (ZrO₂), aluminum oxide (Al₂O₃),indium oxide (In₂O₃), zinc oxide (ZnO), or tin oxide (SnO₂).Alternatively, the first scatterer may be organic particles includingacrylic resin or urethane resin.

The first scatterer may scatter incident light in random directionswithout substantially changing the wavelength of the light transmittedthrough the first wavelength conversion 352. Accordingly, the firstscatterer may increase the length of the path of the light transmittedthrough the first wavelength conversion layer 352, thereby increasingthe color conversion efficiency of the first wavelength shifter.

In an embodiment, the first wavelength conversion layer 352 may overlapthe first color filter 371. Therefore, a portion of short-wavelengthlight such as a blue light or an ultraviolet light provided from thefirst subpixel PX1 may pass through the first wavelength conversionlayer 352 without being converted into light of the first color by thefirst wavelength shifter. In such an embodiment, the short-wavelengthlight such as a blue light or an ultraviolet light incident on the firstcolor filter 371 without being converted by the first wavelengthconversion layer 352 may not pass through the first color filter 371. Insuch an embodiment, light of the first color output from the firstwavelength conversion layer 352 may pass through the first color filter371 and proceed toward the second substrate 112.

The second wavelength conversion layer 353 may overlap the secondsubpixel PX2. The second wavelength conversion layer 353 may convertshort-wavelength light such as a blue light or an ultraviolet lightemitted from the light emitting layer 342 of the second subpixel PX2into light of the second color. In such an embodiment, the secondwavelength conversion layer 353 may include a second base resin, asecond wavelength shifter, and a second scatterer. The second baseresin, the second wavelength shifter and the second scatterer of thesecond wavelength conversion layer 353 are substantially the same asthose of the first wavelength conversion layer 352, and thus anyrepetitive detailed description thereof will be omitted. In anembodiment where the first wavelength shifter and the second wavelengthshifter are quantum dots, the diameter of the second wavelength shiftermay be less than that of the first wavelength shifter.

In an embodiment, the second wavelength conversion layer 353 may overlapthe second color filter 372. Therefore, a portion of short-wavelengthlight such as a blue light or an ultraviolet light provided from thesecond subpixel PX2 may pass through the second wavelength conversionlayer 353 without being converted into light of the second color by thesecond wavelength shifter. In such an embodiment, the short-wavelengthlight such as a blue light or an ultraviolet light incident on thesecond color filter 372 without being converted by the second wavelengthconversion layer 353 may not pass through the second color filter 372.In such an embodiment, light of the second color output from the secondwavelength conversion layer 353 may pass through the second color filter372 and proceed toward the second substrate 112.

The third wavelength conversion layer 354 may overlap the third subpixelPX3. The third wavelength conversion layer 354 may convertshort-wavelength light such as blue light or ultraviolet light emittedfrom the light emitting layer 342 of the third subpixel PX3 into lightof the third color. In such an embodiment, the third wavelengthconversion layer 354 may include a third base resin and a thirdscatterer. The third base resin and the third scatterer of the thirdwavelength conversion layer 354 are substantially the same as those ofthe first wavelength conversion layer 352, and thus any repetitivedetailed description thereof will be omitted.

In such an embodiment, the third wavelength conversion layer 354 mayoverlap the third color filter 373. Therefore, short-wavelength lightsuch as a blue light or an ultraviolet light provided from the thirdsubpixel PX3 may pass through the third wavelength conversion layer 354as it is, and the light that passes through the third wavelengthconversion layer 354 may pass through the third color filter 373 andproceed toward the second substrate 112.

The second capping layer 355 may be disposed on the first wavelengthconversion layer 352, the second wavelength conversion layer 353, thethird wavelength conversion layer 354, and portions of the first cappinglayer 351 not covered by the wavelength conversion layers 352 through354. The second capping layer 355 effectively prevents moisture oroxygen from permeating into the first wavelength conversion layer 352,the second wavelength conversion layer 353 and the third wavelengthconversion layer 354 from the outside. The second capping layer 355 mayinclude or be made of an inorganic layer such as silicon nitride,aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride,tantalum nitride, silicon oxide, aluminum oxide or titanium oxide.

The interlayer organic film 356 may be disposed on the second cappinglayer 355. The interlayer organic film 356 may be a planarization layerfor planarizing steps due to the wavelength conversion layers 352through 354. The interlayer organic film 356 may include or be made ofan organic layer such as acryl resin, epoxy resin, phenolic resin,polyamide resin, or polyimide resin.

The third capping layer 357 may be disposed on the interlayer organicfilm 356. The third capping layer 357 may include or be made of aninorganic layer such as silicon nitride, aluminum nitride, zirconiumnitride, titanium nitride, hathium nitride, tantalum nitride, siliconoxide, aluminum oxide, or titanium oxide.

The filler FL may be disposed between the thin-film encapsulation layer345 disposed on the first substrate 111 and the third capping layer 357disposed on the second substrate 112. The filler FL may include or bemade of a material having a buffer function. In one embodiment, forexample, the filler FL may include or be made of an organic layer suchas acryl resin, epoxy resin, phenolic resin, polyamide resin, orpolyimide resin.

In an embodiment, a sealing material for bonding the first substrate 111and the second substrate 112 may be disposed in the non-display area ofthe display panel 110. When seen in a plan view, the filler FL may besurrounded by the sealing material. The sealing material may be a glassfrit or a sealant.

According to an embodiment, as shown in FIG. 7, the first through thirdsubpixels PX1 through PX3 may emit short-wavelength light such as a bluelight or an ultraviolet light. Light of the first subpixel PX1 isconverted into light of the first color by the first wavelengthconversion layer 352 and then output through the first color filter CF1.Light of the second subpixel PX2 is converted into light of the secondcolor by the second wavelength conversion layer 353 and then outputthrough the second color filter CF2. Light of the third subpixel PX3 isoutput through the third wavelength conversion layer 354 and the thirdcolor filter CF3. Therefore, white light may be output form the displayarea of the display panel 110.

In an embodiment, as shown in FIG. 7, the subpixels PX1 through PX3 area top emission type which emits light toward the second substrate 112,that is, in the upward direction. Therefore, the heat dissipation film130 including an opaque material such as graphite or aluminum may bedisposed on the surface of the first substrate 111.

FIG. 8 is a cross-sectional view showing an embodiment of the firstsound generator 210 and the second sound generator 220 of FIG. 3. FIG. 8is a cross-sectional view taken along line I-I′ of FIG. 3.

Referring to FIG. 8, each of the first sound generator 210 and thesecond sound generator 220 may be an exciter that vibrates the displaypanel 110 by generating a magnetic force using a voice coil. In such anembodiment, holes may be defined in areas of the control circuit board160 where the first sound generator 210 and the second sound generator220 are disposed.

Each of the first sound generator 210 and the second sound generator 220may include a magnet 211, the bobbin 212, a voice coil 213, a damper214, and the lower plate 215.

The magnet 211 is a permanent magnet, and a sintered magnet such asbarium ferrite can be used. The material of the magnet 211 may be, butis not limited to, ferric trioxide (Fe₂O₃), barium carbonate (BaCO₃), aneodymium magnet, strontium ferrite with an improved magnetic component,or an aluminum (Al), nickel (Ni) or cobalt (Co) alloy cast magnet. Theneodymium magnet may be, for example, neodymium-iron-boron (Nd—Fe—B).

The magnet 211 may include a plate 211 a, a central protrusion 211 bprotruding from a center of the plate 211 a, and sidewalls 211 cprotruding edges of the plate 211 a. The central protrusion 211 b andthe sidewalls 211 c may be spaced apart from each other by apredetermined distance. Therefore, a predetermined space may be definedbetween the central protrusion 211 b and each of the sidewalls 211 c. Inan embodiment, the magnet 211 may be shaped like a circular cylinder,e.g., a circular cylinder having a circular space formed in any onebottom surface of the circular cylinder.

The central protrusion 211 b of the magnet 211 may have the magnetism ofa north (N) pole, and the plate 211 a and the sidewalls 211 c may havethe magnetism of a south (S) pole. Therefore, an external magnetic fieldmay be formed between the central protrusion 211 b and the plate 211 bof the magnet 211 and between the central protrusion 211 b and thesidewalls 211 c.

The bobbin 212 may be cylindrical. The central protrusion 211 b of themagnet 211 may be disposed inside the bobbin 212. In such an embodiment,the bobbin 212 may surround the central protrusion 211 b of the magnet211. In such an embodiment, the sidewalls 211 c of the magnet 211 may bedisposed outside the bobbin 212. That is, the sidewalls 211 c of themagnet 211 may surround the bobbin 212. A space may be defined betweenthe bobbin 212 and the central protrusion 211 b of the magnet 211 andbetween the bobbin 212 and the sidewalls 211 c of the magnet 211.

The bobbin 212 may include or be made of a material obtained byprocessing pulp or paper, aluminum or magnesium or an alloy thereof, asynthetic resin such as polypropylene, or a polyamide-based fiber. Anend of the bobbin 212 may be attached to the heat dissipation film 130using an adhesive member. The adhesive member may be a double-sidedtape.

The voice coil 213 is wound on an outer circumferential surface of thebobbin 212. An end of the voice coil 213 which is adjacent to the end ofthe bobbin 212 may receive the (1A)^(th) driving voltage or the(2A)^(th) driving voltage, and the other end of the voice coil 213 whichis adjacent to the other end of the bobbin 212 may receive the (1B)^(th)driving voltage or the (2B)^(th) driving voltage. Therefore, an electriccurrent may flow through the voice coil 213 according to the (1A)^(th)driving voltage or the (2A)^(th) driving voltage and the (1B)^(th)driving voltage or the (2B)^(th) driving voltage. An applied magneticfield corresponding to the electric current flowing through the voicecoil 213 may be formed around the voice coil 213. The direction of theelectric current flowing through the voice coil 213 may be opposite whenthe (1A)^(th) driving voltage or the (2A)^(th) driving voltage is apositive voltage and the (1B)^(th) driving voltage or the (2B)^(th)driving voltage is a negative voltage and when the (1A)^(th) drivingvoltage or the (2A)^(th) driving voltage is a negative voltage and the(1B)^(th) driving voltage or the (2B)^(th) driving voltage is a positivevoltage.

Therefore, the N pole and the S pole of the applied magnetic fieldformed around the voice coil 213 may be changed according to thealternating current (“AC”) driving of the (1A)^(th) driving voltage orthe (2A)^(th) driving voltage and the (1B)^(th) driving voltage or the(2B)^(th) driving voltage. Accordingly, an attractive force and arepulsive force alternately act on the magnet 211 and the voice coil213, such that the bobbin 212 on which the voice coil 213 is woundreciprocates in the third direction (Z-axis direction) as illustrated inFIGS. 10A and 10B. Accordingly, the display panel 110 and the heatdissipation film 130 vibrate in the third direction (Z-axis direction),thereby outputting a sound.

The damper 214 is disposed between a portion of an upper side of thebobbin 212 and the sidewalls 211 c of the magnet 211. The damper 214adjusts the up and down vibration of the bobbin 212 by contacting orrelaxing according to the up and down movement of the bobbin 212. Insuch an embodiment, where the damper 214 is connected to the bobbin 212and the sidewalls 211 c of the magnet 211, the up and down movement ofthe bobbin 212 may be limited by a restoring force of the damper 214. Inone embodiment, for example, when the bobbin 212 vibrates above apredetermined height or vibrates below a predetermined height, it may bereturned to its original position by the restoring force of the damper214.

The lower plate 215 may be disposed on a lower surface of the magnet211. The lower plate 215 may be formed integrally with the magnet 211 ormay be formed separately from the magnet 211. In an embodiment, wherethe lower plate 215 is formed separately from the magnet 211, the magnet211 may be attached to the lower plate 215 with an adhesive member suchas a double-sided tape.

The lower plate 215 may be fixed to the control circuit board 160 by afixing members 216 such as a screw. Accordingly, the magnet 211 of eachof the first sound generator 210 and the second sound generator 220 maybe fixed to the control circuit board 160.

In an embodiment, as described above, the magnet 211 of each of thefirst sound generator 210 and the second sound generator 220 is fixed tothe control circuit board 160, but embodiments of the specification arenot limited thereto. Alternatively, the magnet 211 of each of the firstsound generator 210 and the second sound generator 220 may be fixed tothe system circuit board, the power circuit board, or a dummy circuitboard instead of the control circuit board 160. The dummy circuit boardrefers to a circuit board on which any other circuit other than thefirst sound generator 210 or the second sound generator 220 is notdisposed. In an embodiment, the first sound generator 210 or the secondsound generator 220 is only disposed on the dummy circuit board. Thedummy circuit board may be a flexible printed circuit board or a printedcircuit board.

The first buffer member 190 may be attached to the second surface of thecontrol circuit board 160. The height of the first buffer member 190 isless than the distance between the surface of the heat dissipation film130 and the second surface of the control circuit board 160. Therefore,a gap may exist between the first buffer member 190 and the heatdissipation film 130. The gap between the first buffer member 190 andthe heat dissipation film 130 may be less than a gap between the heatdissipation film 130 and the lower cover 180. The first buffer member190 may include a material having elasticity.

FIG. 9 is a cross-sectional view of an embodiment of a first buffermember illustrated in FIG. 8.

In an embodiment the first buffer member 190 may include a first basefilm 191, a first buffer layer 192, a first sacrificial layer 193, andan adhesive layer 194 as illustrated in FIG. 9.

The first base film 191 may include or be made of a plastic. In oneembodiment, for example, the first base film 191 may be PET.

The first buffer layer 192 may be disposed on a surface of the firstbase film 191. The first buffer layer 192 may including or be made of afoam having elasticity. in one embodiment, for example, the first bufferlayer 192 may include or be made of polyurethane, silicone, rubber, oraerogel. The first sacrificial layer 193 may be disposed on a surface ofthe first buffer layer 192. The first sacrificial layer 193 may beseparated when the first buffer member 190 has to be detached afterbeing wrongly attached. In such an embodiment, the adhesive layer 194and a portion of the first sacrificial layer 193 may remain on thesecond surface of the lower cover 180. The first sacrificial layer 193may include or be made of a material with low elasticity. In oneembodiment, for example, the first sacrificial layer 193 may include orbe made of polyurethane. Alternatively, the first sacrificial layer 193may be omitted.

The adhesive layer 194 may be disposed on a surface of the firstsacrificial layer 193. The adhesive layer 194 may be attached onto thesecond surface of the lower cover 180. The adhesive layer 194 may be,but is not limited to, an acrylic adhesive or a silicone adhesive.

In an alternative embodiment, a first buffer layer 190′ may be definedby or formed as metal springs as illustrated in FIG. 12. In such anembodiment, each second fixing member 217 may have a protrusion 217 adisposed through the control circuit board 160 and protruding from thesecond surface of the control circuit board 160. The protrusion 217 amay be inserted into the first buffer member 190′. An end of the firstbuffer member 190′ may contact the second surface of the lower cover180, and the other end may contact the surface of the heat dissipationfilm 130. Alternatively, a side of the first buffer member 190′ maycontact the second surface of the lower cover 180, but the other end maynot contact the surface of the heat dissipation film 130. In such anembodiment, a gap may exist between the first buffer member 190′ and theheat dissipation film 130.

The operation of the first buffer member 190 will hereinafter bedescribed in detail with reference to FIGS. 10A, 10B and 11.

FIGS. 10A and 10B illustrate a vibration of the display panel by thefirst sound generator of FIG. 8, and FIG. 11 is a graph illustrating thevibration displacement with respect to the vibration frequency of thedisplay panel by the first sound generator.

In FIG. 11, the x axis represents the vibration frequency of the displaypanel 110, and they axis represents the vibration displacement of thedisplay panel 110.

Referring to FIGS. 10A and 10B, the display panel 110 is vibrated up anddown by the first sound generator 210 or the second sound generator 220,and sound may be output by the vibration of the display panel 110.Referring to FIG. 11, when the vibration frequency of the display panel110 is about 200 hertz (Hz) or more, the vibration displacement of thedisplay panel 110 is in a range of negative several hundreds ofmicrometers to positive several hundreds of micrometers. When thevibration frequency of the display panel 110 is lower than about 200 Hz,the vibration displacement of the display panel 110 is in a range of−3000 micrometers (μm) to 3000 μm. Therefore, if the distance betweenthe heat dissipation film 130 and the lower cover 180 is 3 millimeters(mm) or less, the display panel 110 may collide with the lower cover 180and be damaged when the display panel 110 is vibrated to producelow-pitched sound by the first sound generator 210 or the second soundgenerator 220.

In an embodiment of the invention, as described above, the displaydevice 10 includes the first buffer member 190 which is attached ontothe second surface of the control circuit board 160, is spaced apartfrom the heat dissipation film 130 by a gap less than the gap betweenthe heat dissipation film 130 and the lower cover 180, and includes amaterial having elasticity. Therefore, when the vibration displacementof the display panel 110 is large, the display panel 110 may collidewith the first buffer member 190 before colliding with the lower cover180. Since the first buffer member 190 includes a material havingelasticity, even if the first buffer member 190 collides with thedisplay panel 110, the display panel 110 may not be damaged. Therefore,the first buffer member 190 may effectively prevent the display panel110 from colliding with the lower cover 180 and being damaged.

FIG. 13 is an enlarged view of area A of FIG. 5.

Referring to FIG. 13, an embodiment of the blocking member 200 mayinclude a second base film 201, a second buffer layer 202, a secondsacrificial layer 203, a first adhesive layer 204, and a second adhesivelayer 205.

The second base film 201, the second buffer layer 202, the secondsacrificial layer 203, and the first adhesive layer 204 of the blockingmember 200 may be substantially the same as the first base film 191, thefirst buffer layer 192, the first sacrificial layer 193 and the adhesivelayer 194 of the first buffer member 190 described above with referenceto FIG. 9. Therefore, any repetitive detailed description of the secondbase film 201, the second buffer layer 202, the second sacrificial layer203 and the first adhesive layer 204 of the blocking member 200 will beomitted.

In such an embodiment, the second adhesive layer 205 may be disposed ona second surface of the second base film 201. The second adhesive layer205 may be attached onto the surface of the heat dissipation film 130.The second adhesive layer 205 may be, but is not limited to, an acrylicadhesive or a silicone adhesive.

FIG. 14 is a perspective view of an embodiment of the third soundgenerator 230 and the fourth sound generator 240 of FIG. 4. FIG. 15 is across-sectional view taken along line of FIG. 14.

Referring to FIGS. 14 and 15, each of the third sound generator 230 andthe fourth sound generator 240 may be a piezoelectric element thatvibrates the display panel 110 by contracting or expanding in responseto a voltage applied thereto. In such an embodiment, each of the thirdsound generator 230 and the fourth sound generator 240 may include avibration layer 511, a first electrode 512, and a second electrode 513.

The first electrode 512 may include a first stem electrode 5121 andfirst branch electrodes 5122. The first stem electrode 5121 may bedisposed on only one side surface of the vibration layer 511 or on aplurality of side surfaces of the vibration layer 511 as illustrated inFIG. 14. The first stem electrode 5121 may also be disposed on an uppersurface of the vibration layer 511. The first branch electrodes 5122 mayextend or branch from the first stem electrode 5121. The first branchelectrodes 5122 may be arranged parallel to each other.

The second electrode 513 may include a second stem electrode 5131 andsecond branch electrodes 5132. The second stern electrode 5131 may bedisposed on another side surface of the vibration layer 511 or may bedisposed on a plurality of side surfaces of the vibration layer 511 asillustrated in FIG. 14. Here, as illustrated in FIG. 14, the first sternelectrode 5121 may be disposed on any one of the side surfaces on whichthe second stern electrode 5131 is disposed. The second stem electrode5131 may be disposed on the upper surface of the vibration layer 511.The first stem electrode 5121 and the second stem electrode 5131 may notoverlap each other. The second branch electrodes 5132 may extend orbranch from the second stem electrode 5131. The second branch electrodes5132 may be arranged parallel to each other.

In an embodiment, the first branch electrodes 5122 and the second branchelectrodes 5132 may be arranged parallel to each other in the horizontaldirection (X-axis direction or Y-axis direction). In such an embodiment,the first branch electrodes 5122 and the second branch electrodes 5132may be alternately arranged in the vertical direction (Z-axisdirection). That is, the first branch electrodes 5122 and the secondbranch electrodes 5132 may be repeatedly arranged in the verticaldirection (Z-axis direction) in the order of the first branch electrode5122, the second branch electrode 5132. the first branch electrode 5122,and the second branch electrode 5132.

The first electrode 512 and the second electrode 513 may be connected tometal lines or pad electrodes of the first sound circuit board 250 orthe second sound circuit board 260. The metal lines or pad electrodes ofthe first sound circuit board 250 or the second sound circuit board 260may be connected to the first electrode 512 and the second electrode 513disposed on the surface of the third sound generator 230 or the fourthsound generator 240.

The vibration layer 511 may be a piezoelectric element that is deformedaccording to a first driving voltage applied to the first electrode 512and a second driving voltage applied to the second electrode 513. Insuch an embodiment, the vibration layer 511 may include a piezoelectricmaterial such as a polyvinylidene fluoride (“PVDF”) film or plumbumziconate titanate (“PLT”) and an electroactive polymer.

Since the production temperature of the vibration layer 511 is high, thefirst electrode 512 and the second electrode 513 may include or be madeof silver (Ag) having a high melting point or an alloy of Ag andpalladium (Pd). In an embodiment, where the first electrode 512 and thesecond electrode 513 include or are made of an alloy of Ag and Pd, thecontent of Ag may be higher than that of Pd to increase the meltingpoints of the first electrode 512 and the second electrode 513.

The vibration layer 511 may be disposed between the first branchelectrodes 5122 and the second branch electrodes 5132. The vibrationlayer 511 contracts or expands based on the difference between the firstdriving voltage applied to a first branch electrode 5122 and the seconddriving voltage applied to a second branch electrode 5132.

In an embodiment, as illustrated in FIG. 15, the polarity direction ofthe vibration layer 511 disposed between a first branch electrode 5122and a second branch electrode 5132 disposed under the first branchelectrode 5122 may be an upward direction (↑). In such an embodiment,the vibration layer 511 has a positive polarity in an upper areaadjacent to the first branch electrode 5122 and a negative polarity in alower area adjacent to the second branch electrode 5132. In such anembodiment, the polarity direction of the vibration layer 511 disposedbetween a second branch electrode 5132 and a first branch electrode 5122disposed under the second branch electrode 5132 may be a downwarddirection (↓). In such an embodiment, the vibration layer 511 has anegative polarity in an upper area adjacent to the second branchelectrode 5132 and a positive polarity in a lower area adjacent to thefirst branch electrode 5122. The polarity direction of the vibrationlayer 511 may be determined by a poling process of applying an electricfield to the vibration layer 511 usinu a first branch electrode 5122 anda second branch electrode 5132.

Referring to FIG. 16, when the (3A)^(th) driving voltage or the(4A)^(th) driving voltage of the positive polarity is applied to thefirst branch electrode 5122 and the (3B)^(th) driving voltage or the(4B)^(th) driving voltage of the negative polarity is applied to thesecond branch electrode 5132, the polarity direction of the vibrationlayer 511 disposed between a first branch electrode 5122 and a secondbranch electrode 5132 disposed under the first branch electrode 5122 isthe upward direction (↑) such that the vibration layer 511 may contractaccording to a first force F1. The first force F1 may be a compressiveforce. In such an embodiment, when the (3A)^(th) driving voltage or the(4A)^(th) driving voltage of the negative polarity is applied to thefirst branch electrode 5122 and the (3B)^(th) driving voltage or the(4B)^(th) driving voltage of the positive polarity is applied to thesecond branch electrode 5132, the vibration layer 511 may expandaccording to a second force F2. The second force F2 may be a tensileforce.

In an embodiment, referring to FIG. 16, the (3A)^(th) driving voltage orthe (4A)^(th) driving voltage of the positive polarity is applied to thesecond branch electrode 5132 and the (3B)^(th) driving voltage or the(4B)^(th) driving voltage of the negative polarity is applied to thefirst branch electrode 5122, the polarity direction of the vibrationlayer 511 disposed between a second branch electrode 5132 and a firstbranch electrode 5122 disposed under the second branch electrode 5132 isthe downward direction (↓), such that the vibration layer 511 may expandaccording to a tensile force. In such an embodiment, when the (3A)^(th)driving voltage or the (4A)^(th) driving voltage of the negativepolarity is applied to the second branch electrode 5132 and the(3B)^(th) driving voltage or the (4B)^(th) driving voltage of thepositive polarity is applied to the first branch electrode 5122, thevibration layer 511 may contract according to a compressive force. Thesecond force F2 may be a tensile force.

According to an embodiment as illustrated in FIGS. 14 and 15. when the(3A)^(th) driving voltage or the (4A)^(th) driving voltage applied tothe first electrode 512 and the (3B)^(th) driving voltage or the(4B)^(th) driving voltage applied to the second electrode 513 repeatedlyalternate between the positive polarity and the negative polarity, thevibration layer 511 may repeatedly contact and expand, thereby causingthe third sound generator 230 and the fourth sound generator 240 tovibrate.

In an embodiment, each of the third sound generator 230 and the fourthsound generator 240 is disposed on the lower surface of the displaypanel 110, the display panel 110 may vibrate up and down due to stress,as illustrated in FIGS. 17A and 17B when the vibration layer 511 of eachof the third sound generator 230 and the fourth sound generator 240contracts and expands. Accordingly, the display panel 110 is vibrated byeach of the third sound generator 230 and the fourth sound generator240, such that the display device 10 may output a sound.

FIG. 18 is a bottom view of an embodiment of the display device 10 ofFIG. 2.

The embodiment of FIG. 18 is substantially the same as the embodiment ofFIG. 3 except that a first buffer ember 190 surrounds each of a firstsound generator 210 and a second sound generator 220 but is not formedcontinuously.

FIG. 19 is a bottom view of an alternative embodiment of the displaydevice 10 of FIG. 2.

The embodiment of FIG. 19 is substantially the same as the embodiment ofFIG. 3 except that a first buffer member 190 surrounds each of a firstsound generator 210 and a second sound generator 220 in a square shapewhen seen in a plan view. The shape in which the first buffer member 190is disposed when seen in a plan view is not limited to the circularshape illustrated in FIG. 3 and the square shape illustrated in FIG. 19.In one embodiment, for example, the shape in which the first buffermember 190 is disposed when seen in a plan view may be an ellipticalshape or a polygonal shape other than the square shape.

FIG. 20 is a bottom view of another alternative embodiment of thedisplay device 10 of FIG. 2.

The embodiment of FIG. 20 is substantially the same as the embodiment ofFIG. 19 except that a first buffer member 190 surrounds each of a firstsound generator 210 and a second sound generator 220 in a square shapewhen seen in a plan view but is not formed continuously.

FIG. 21 is a bottom view of another alternative embodiment of thedisplay device 10 of FIG. 2.

The embodiment of FIG. 21 is substantially the same as the embodiment ofFIG. 3 except that first buffer members 190 a are disposed adjacent toeach of a first sound generator 210 and a second sound generator 220when seen in a plan view.

Referring to FIG. 21, each of the first buffer members 190 a may beformed as or in a shape of a square dot when seen in a plan view. Whenseen in a plan view, the first buffer members 190 a may be disposed onupper left, upper right, lower left and lower right sides of each of thefirst sound generator 210 and the second sound generator 220. Here, adistance between the first sound generator 210 and the first buffermember 190 a disposed on the upper left side of the first soundgenerator 210, a distance between the first sound generator 210 and thefirst buffer member 190 a disposed on the upper right side of the firstsound generator 210, a distance between the first sound generator 210and the first buffer member 190 a disposed on the lower left side of thefirst sound generator 210, and a distance between the first soundgenerator 210 and the first buffer member 190 a disposed on the lowerright side of the first sound generator 210 may be, but are not limitedto, substantially the same as each other.

In such an embodiment, as shown in FIG. 21, four first buffer members190 a are disposed adjacent to each of the first sound generator 210 andthe second sound generator 220, but the number of the first buffermembers 190 a disposed adjacent to each of the first sound generator 210and the second sound generator 220 is not limited to four and may alsobe two or more.

FIG. 22 is a bottom surface of another alternative embodiment of thedisplay device 10 of FIG. 2.

The embodiment of FIG. 22 is substantially the same as the embodiment ofFIG. 21 except that each of first buffer members 190 b is in a shape ofor formed as a circular dot.

However, the shape of each of the first buffer members 190 b is notlimited to a square dot illustrated in FIG. 21 or a circular dotillustrated in FIG. 22. In one embodiment, for example, the shape ofeach of the first buffer members 190 b may also be an elliptical dot ora polygonal dot other than a square dot.

In an embodiment, as shown in FIGS. 21 and 22, all of the first buffermembers 190 b have the same shape as each other, but the disclosure isnot limited thereto. Alternatively, all of the first buffer members 190b may also have different shapes. Alternatively, at least two of thefirst buffer members 190 b may have different shapes.

FIG. 23 is a bottom view of another alternative embodiment of thedisplay device 10 of FIG. 2. FIG. 24 is a side view of the displaydevice 10 of FIG. 26. FIG. 25 is a cross-sectional view take along lineIV-IV′ of FIG. 23.

The embodiment of FIGS. 23 through 25 is substantially the same as theembodiment of FIGS. 3, 5 and 8 except that a first sound generator 210and a second sound generator 220 are not fixed to a control circuitboard 160, but are fixed to a lower cover 180.

Referring to FIGS. 23 through 25, in an embodiment where the first soundgenerator 210 and the second sound generator 220 are disposed not on thecontrol circuit board 160 but on the lower cover 180, the first soundgenerator 210 and the second sound generator 220 may be fixed to thelower cover 180. In such an embodiment, a lower plate 215 of each of thefirst sound generator 210 and the second sound generator 220 may befixed to the lower cover 180 by a fixing member 216′ such as a screw.Accordingly, a magnet 211 of each of the first sound generator 210 andthe second sound generator 220 may be fixed to the lower cover 180. Insuch an embodiment, the first buffer member 190 may be disposed on asecond surface of the lower cover 180, not on a second surface of thecontrol circuit board 160.

The first sound generator 210 may be electrically connected to thecontrol circuit board 160 by a first sound signal line WL1 and a secondsound signal line WL2. in an embodiment, an end of the first soundsignal line WL1 may be connected to an end of a voice coil 213 of thefirst sound generator 210, and an end of the second signal line WL2 maybe connected to the other end of the voice coil 213 of the first soundgenerator 210. The other end of the first sound signal line WL1 and theother end of the second sound signal line WL2 may be connected to metallines of the control circuit board 160. In such an embodiment, the firstsound generator 210 may receive a (1A)^(th) driving voltage of a firstsound signal of a sound driving circuit 171 through the first soundsignal line WL1 and may receive a (1B)^(th) driving voltage of the firstsound signal of the sound driving circuit 171 through the second soundsignal line WL2. The first sound generator 210 may output sound byvibrating a display panel 110 in response to the (1A)^(th) drivingvoltage and the (1B)^(th) driving voltage.

The second sound generator 220 may be electrically connected to thecontrol circuit board 160 by a third sound signal line WL3 and a fourthsound signal line WL4. In an embodiment, an end of the third soundsignal line WL3 may be connected to an end of a voice coil 213 of thesecond sound generator 220, and an end of the fourth signal line WL4 maybe connected to the other end of the voice coil 213 of the second soundgenerator 220. The other end of the third sound signal line WL3 and theother end of the fourth sound signal line WL4 may be connected to metallines of the control circuit board 160. In such an embodiment, thesecond sound generator 220 may receive a (2A)^(th) driving voltage of asecond sound signal of the sound driving circuit 171 through the thirdsound signal line WL3 and may receive a (2B)^(th) driving voltage of thesecond sound signal of the sound driving circuit 171 through the fourthsound signal line WL4. The second sound generator 220 may output soundby vibrating the display panel 110 in response to the (2A)^(th) drivingvoltage and the (2B)^(th) driving voltage.

FIG. 26 is a bottom view of another alternative embodiment of thedisplay device 10 of FIG. 2. FIG. 27 is a bottom view of an embodimentof the display device 10 of FIG. 26 when a lower cover 180 and a controlcircuit board 160 are omitted from FIG. 26. FIG. 28 is a side view ofthe display device 10 of FIG. 26. The embodiment of FIGS. 26 through 28is substantially the same as the embodiment of FIGS. 3 through 5 exceptthat flexible films 122 are bent toward a lower surface of the lowercover 180 and that source circuit boards 140 and the control circuitboard 160 are disposed on a first surface of the lower cover 180.

Referring to FIGS. 26 through 28, in an embodiment, the flexible films122 may be bent toward the lower surface of the lower cover 180.Accordingly, the source circuit boards 140 and the control circuit board160 may be disposed on the first surface of the lower cover 180.Therefore, cables 150 connecting the source circuit boards 140 and thecontrol circuit board 160 may pass through first cable holes CH1 definedthrough the lower cover 180.

A first sound circuit board 250 connected to a third sound generator 230may be connected to a connector 153 of the control circuit board 160through a second cable hole CH2 defined through the lower cover 180.

A second sound circuit board 260 connected to a fourth sound generator240 may also be connected to another connector of the control circuitboard 160 through another second cable hole CH2 defined through thelower cover 180.

FIG. 29 is a bottom view of another alternative embodiment of thedisplay device 10 of FIG. 2. FIG. 30 is a side view of the displaydevice 10 of FIG. 29.

The embodiment of FIGS. 29 and 30 is substantially the same as theembodiment of FIGS. 3 and 5 except that a first sound generator 210 anda second sound generator 220 are not fixed to a control circuit board160, but are fixed to a lower cover 180. In addition, the embodiment ofFIGS. 29 and 30 is different from the embodiment of FIGS. 3 and 5 inthat flexible films 122 are bent toward a lower surface of the lowercover 180 and that source circuit boards 140 are disposed on a firstsurface of the lower cover 180.

The embodiment of FIGS. 29 and 30 is substantially the same as theembodiment of FIGS. 23 through 25 in that the first sound generator 210and the second sound generator 220 are not fixed to the control circuitboard 160, but are fixed to the lower cover 180. In addition, theembodiment of FIGS. 29 and 30 is substantially the same as theembodiment of FIGS. 26 through 28 in that the flexible films 122 arebent toward the lower surface of the lower cover 180 and that the sourcecircuit boards 140 are disposed on the first surface of the lower cover180. Therefore, any repetitive detailed description of such elements ofFIGS. 29 and 30 will be omitted.

In embodiments of the invention, a display device outputs sound using adisplay panel as a diaphragm through a sound generator. Therefore, sincesound may be output from the front of the display device, sound qualitymay be improved. In such embodiments, the sound generator allows aspeaker typically disposed on a lower surface or a side of aconventional display panel to be omitted.

In embodiments of a display device, a buffer member is attached to asecond surface of a circuit board or a lower cover. Therefore, when adisplay panel is vibrated by a sound generator, the display panel may beeffectively prevented from colliding with the lower cover and beingdamaged.

In embodiments of a display device, a sound generator and a sourcecircuit board are connected by a sound circuit board. Therefore, even ifthe sound generator is disposed on a surface of a heat dissipation filmand a control circuit board is disposed on a surface of a lower cover,the control circuit board and the sound generator may be easilyelectrically connected to each other.

In embodiments of a display device, each sound generator is surroundedby a blocking member. Therefore, the effect of vibrations of a displaypanel generated by each sound generator on vibrations of the displaypanel generated by an adjacent sound generator may be effectivelyprevented or substantially reduced.

However, the effects of the embodiments are not restricted to the oneset forth herein. The above and other effects of the embodiments willbecome more apparent to one of daily skill in the art to which theembodiments pertain by referencing the claims.

While the inventions have been particularly shown and described withreference to some embodiments thereof, it will be understood by one ofordinary skill in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the following claims.

What is claimed is:
 1. A display device comprising: a display panelcomprising a first substrate, a second substrate, and a light emittingelement layer disposed between the first substrate and the secondsubstrate, wherein the light emitting element layer outputs light to thesecond substrate; a first sound generator disposed on a surface of thefirst substrate, wherein the first sound generator vibrates the displaypanel to output a sound; and a first buffer member disposed on thesurface of the first substrate, wherein a height of the first buffermember is less than a height of the first sound generator.
 2. Thedisplay device of claim 1, further comprising: a lower cover disposed onthe surface of the first substrate; and a circuit board disposed on afirst surface of the lower cover.
 3. The display device of claim 2,wherein a the first substrate and the first buffer member is spacedapart from each other with a gap therebetween.
 4. The display device ofclaim 3, wherein the height of the first buffer member is less than adistance between the surface of the first substrate and a second surfaceof the lower cover, which is opposite to the first surface.
 5. Thedisplay device of claim 2, wherein the first buffer member comprises: afirst base film; a first buffer layer disposed on a surface of the firstbase film; an adhesive layer disposed on the first buffer layer; and afirst sacrificial layer disposed between the first buffer layer and theadhesive layer.
 6. The display device of claim 5, wherein the adhesivelayer is attached to the lower cover or the circuit board.
 7. Thedisplay device of claim 2, wherein the first buffer member is attachedto a second surface of the lower cover which faces the surface of thefirst substrate.
 8. The display device of claim 7, wherein a gap betweenthe first substrate and the first buffer member is less than a gapbetween the first substrate and the lower cover.
 9. The display deviceof claim 7, further comprising: a blocking member disposed between thefirst substrate and the lower cover.
 10. The display device of claim 2,wherein the first buffer member is attached to a surface of the circuitboard which faces the surface of the first substrate.
 11. The displaydevice of claim 10, wherein the height of the first buffer member isless than a distance between the surface of the first substrate and thesurface of the circuit board.
 12. The display device of claim 10,further comprising: a blocking member which is disposed between thefirst substrate and the circuit board.
 13. The display device of claim12, wherein a height of the blocking member is greater than the heightof the first buffer member.
 14. The display device of claim 12, whereinthe blocking member comprises: a second base film; a second buffer layerdisposed on a surface of the second base film; a first adhesive layerdisposed on the second buffer layer; a second adhesive layer disposed onanother surface of the second base film; and a second sacrificial layerdisposed between the second buffer layer and the first adhesive layer.15. The display device of claim 14, further comprising: a heatdissipation film attached onto the surface of the first substrate,wherein the first adhesive layer is attached to the heat dissipationfilm, and wherein the second adhesive layer is attached to the lowercover or the circuit board.
 16. The display device of claim 2, furthercomprising: a timing control circuit disposed on the circuit board,wherein the timing control circuit controls a driving timing of thedisplay panel.
 17. The display device of claim 2, further comprising: asound driving circuit disposed on the circuit board, wherein the sounddriving circuit outputs a first sound signal to the first soundgenerator.
 18. The display device of claim 2, further comprising: afixing member which fixes the circuit board to the lower cover, whereinthe fixing member comprises a protrusion which is disposed through thelower cover and the circuit board and protrudes from a second surface ofthe lower cover, which is opposite to the first surface, wherein theprotrusion is inserted into the first buffer member.
 19. The displaydevice of claim 2, wherein the first sound generator comprises: a bobbindisposed on the surface of the first substrate; a voice coil whichsurrounds the bobbin; a magnet disposed on the bobbin and spaced apartfrom the bobbin; and a lower plate disposed on the magnet and fixed tothe lower cover or the circuit board by a fixing member.
 20. The displaydevice of claim 2, further comprising: a third sound generator disposedon the surface of the first substrate; and a sound circuit boardelectrically connected to the third sound generator to transmit a soundsignal to the third sound generator.
 21. The display device of claim 20,wherein the third sound generator comprises: a first electrode whichreceives a first driving voltage; a second electrode which receives asecond driving voltage; and a vibration layer disposed between the firstelectrode and the second electrode, wherein the vibration layercomprises a piezoelectric element which contracts or expands in responseto the first driving voltage applied to the first electrode and thesecond driving voltage applied to the second electrode.
 22. The displaydevice of claim 20, further comprising: flexible films connected to thefirst substrate of the display panel; a source circuit board connectedto the flexible films; and a cable which connects the circuit board andthe source circuit board to each other.
 23. The display device of claim22, wherein a first hole is defined through the lower cover, and thecable is disposed through the first hole.
 24. The display device ofclaim 23, wherein the source circuit board is disposed on the surface ofthe first substrate, and the circuit board is disposed on the firstsurface of the lower cover.
 25. The display device of claim 22, whereina second hole is defined through the lower cover, and the sound circuitboard is disposed through the second hole.
 26. The display device ofclaim 25, wherein the source circuit board and the circuit board aredisposed on the first surface of the lower cover.
 27. The display deviceof claim 20, further comprising: a second buffer member which overlapsthe third sound generator, wherein the second buffer member and thethird sound generator are spaced apart from each other with a gaptherebetween.
 28. The display device of claim 20, further comprising: asecond buffer member disposed on the third sound generator, wherein thesecond buffer member and the lower cover are spaced apart from eachother with a gap therebetween.
 29. A display device comprising: adisplay panel comprising a first substrate; a lower cover disposed on asurface of the first substrate; a first sound generator disposed on thesurface of the first substrate, wherein the first sound generatorvibrates the display panel to output a sound; and a first buffer memberdisposed on the surface of the first substrate, wherein a height of thefirst buffer member is equal to or less than a distance between thefirst substrate and the lower cover.